Yes, that's exactly the situation I was thinking of. George Lucas made the Special Edition versions, and now there are rumors that he's thinking of making another Special Edition (Special Special Edition?) digitally adding in characters from Episodes 1-3. The mind boggles.
I'm still trying to find out what happened to The Empure Strikes Back in the theaters between the time I saw it the first week it came out, and then three months later. I distinctly remember Yoda riding in Luke's backpack, throwing rocks in front of him for his lightsaber. That scene disappeared in a later theatrical version, yet I remember seeing it.
BTW, did the scene with Luke using R2D2 as a fire hydrant for washing off his X-wing ever reappear in any version? Or did I imagine that scene, too?